The ultrasonic front-end device plays an important role in an ultrasonic diagnostic system. The number of reception channels in an ultrasonic diagnostic system determines the system cost as well as the system performance. There is a need to develop an ultrasonic front-end with good compatibility to satisfy the requirements of ultrasonic diagnostic systems with various performances, which may mitigate workload in development of an ultrasonic diagnostic system, thus decreasing cost in development of the ultrasonic diagnostic system and reducing future cost in maintenance of the ultrasonic diagnostic system.
When an ultrasonic diagnostic system is carrying out ultrasonic transmissions and receptions, due to the changes of the number of scan lines, the transmission and reception channels will choose to operate different array elements in the probe of the ultrasonic diagnostic system every time. Thus, the transmission and reception channels need to be reordered in both the transmission and reception processing, Reordering methods may be classified into analog reordering and digital reordering. Compared with analog reordering, digital reordering has the advantage of having higher reliability and lower cost. Therefore, it is of great importance for the ultrasonic front-end device to have a digital reordering unit, which is highly real time and consumes less hardware resources.
As shown in FIG. 1, a prior-art ultrasonic system 1 mainly comprises a probe 2, an ultrasonic front-end 3, a detector 4, a DSC (Digital Scan Conversion) unit 5, a display 6, and a primary controller 7, wherein the primary controller 7 is configured to perform man-machine interaction and control operations of the ultrasonic front-end device 3, the detector 4 and the DSC unit 5. The ultrasonic front-end device 3 includes two parts: an ultrasonic transmission part 31 and an ultrasonic reception part 32. The ultrasonic transmission part 31 comprises a transmission beamformer 311, a transmission drive unit 312 and a high-voltage analog switch 313. High-voltage transmission pulses originated from the ultrasonic transmission part 31 are fed into the probe 2, to activate the array elements 9 included in the probe 2 to emit ultrasonic waves. The probe 2 receives echoes of the ultrasonic waves, converts them into electric signals and provides the electric signals to the ultrasonic reception part 32. The ultrasonic receiving part 32 comprises a high-voltage analog switch 321, a high-voltage isolation circuit 322, an amplifier 323, an analog reordering unit 324, an ADC (Analog-to-Digital Converter) 325 and a reception beamformer 326. The electric signals received from the probe 2 are amplified, analog reordered and AD (Analog-to-Digital) converted and ultimately the received beam signals are formed. The detector 4 detects the beamformed signals received from the ultrasonic front-end 3, so as to acquire information to be displayed and feeds the information into the DSC unit 5. The DSC unit 5 coordinates transformation of the information and provides the transformed information to the display 6 for presentation. The analog reordering unit 324 is typically implemented with an expensive matrix of analog switches or a multi-stage analog switch.
The number of transmission and reception channels (especially the reception channels) in most conventional ultrasonic systems is less than the number of array elements Included in the probe, thus high-voltage analog switches have to be employed to select a suitable number of array elements from those included in the probe, for connection to their respective channels. The conventional ultrasonic systems may be classified into two types: type A and type B. For type A, the transmission and reception channels of an ultrasonic system share a single high-voltage analog switch and thus one high-voltage analog switch may be saved. However it brings difficulty in the implementation of synthetic aperture. For type B, the transmission and reception channels of an ultrasonic system use their own high-voltage analog switches, respectively, as shown in FIG. 1. Technical solutions disclosed in U.S. Pat. No. 5,817,862, No. 6,029,116, No. 5,882,307 and No. 5,551,433 relate to Type B ultrasonic systems, with an advantage of allowing the aperture of the reception channels and that of the transmission channels to have different sizes and thus provides a possibility to implement various aperture synthesis techniques.
The conventional ultrasonic system of FIG. 1 has several drawbacks. First, the use of high-voltage analog switches leads to high cost of the ultrasonic system. Second, the analog reordering unit adopts a multi-stage analog switch, thus affecting the quality of signal reception. Third, the use of high-voltage analog switches and multi-stage analog switches results in poor stability of the ultrasonic system.
There exists another type of ultrasonic system in the prior arts. This ultrasonic system is different from the one of FIG. 1 in that its ultrasonic transmission part has digital reordering function, but its ultrasonic reception part has no analog reordering unit and the reception beamformer has digital reordering function. As shown in FIG. 2, the ultrasonic transmission part 31 in the ultrasonic system 1 comprises a transmission beamformer 311, transmission driving units 312 and a high-voltage analog switch 313 connected in a sequential order. Referring to FIG. 3, the transmission beamformer 311 comprises a transmission parameter storing unit 3111 and a transmission parameter digital reordering unit 3112 whose output is provided to the transmission driving unit 312. As shown in FIG. 6, a digital reordering unit 40, such as the transmission parameter digital reordering unit 3112 of FIG. 3, comprises M M:1 multiplexers 41 followed by M corresponding D-type flip-flops (DFFs) 42, so as to implement a selection from M inputs to M outputs, where M denotes the number of array elements included in the probe of the ultrasonic system.
Furthermore, the ultrasonic reception part 32 comprises a high-voltage analog switch 321, a high-voltage Isolation circuit 322, amplifiers 323, ADCs 325 and a reception beamformer 326 with digital reordering function, all of them serially connected. The reception beamformers having digital reordering function in prior arts may be classified into two types. The first type of reception beamformer for performing digital reordering on the received parameters is shown in FIG. 4. The reception beamformer 326 comprises delay units 3281, a delay parameter read controller 3262, a delay parameter digital reordering unit 3283, apodization units 3284, an apodization parameter read controller 3265, an apodization parameter digital reordering unit 3288 and an adding unit 3267. The reception beamformer 328 delays, apodises and adds the signals received from the ADCs 325, to synthesize the received beam signals. The second type of reception beamformer for performing digital reordering on the received signals is shown in FIG. 5. The reception beamformer 328 comprises a signal digital reordering unit 3288, delay units 3261, a delay parameter read controller 3282, apodization units 3264, anapodization parameter read controller 3265 and an adding unit 3267. The reception beamformer 326 delays, apodises, reorders and adds the signals received from the ADCs 325, so as to synthesize the received beam signals. The prior art of the digital reordering method is shown in FIG. 6. M M:1 multiplexers are used to complete the selection from M Inputs to M outputs. This architecture is not optimal, because the delay from the inputs to outputs is large, and it consumes much hardware resource.
An ultrasonic diagnosing system disclosed in a U.S. patent application with publication No. 20060074317A has a function similar to digital reordering, but it fails to present a specific structure which may be real time and consumes less hardware resources.
A Chinese patent application with publication No. CN1649645A discloses an ultrasonic diagnostic equipment, which comprises an ultrasonic transmission part and an ultrasonic reception part. The ultrasonic reception part comprises a limiter (i.e. isolation circuit), low-voltage analog switches and ADCs. A cross point switch network is connected between these low-voltage switches and ADCs, for reordering and adding the received signals and providing the resultant signals to the ADCs for AD conversion. The ultrasonic diagnostic equipment has the drawbacks of incapable of implementing an ultrasonic system with a different number of channels.